Calculating number of users to watch streaming video ?

Hi,
I am trying to calculate the number of users, for a one to many, video on demand application. I have 300 videos on the server.

80000Mb (Bandwidth) = No. of users * 400kbs (encoded video)
Therefore:
No. of users = 200.

If this is correct, does this mean that only 200 users can view the same one video simultaneously ? Or is it that only 200 users can view my videos (all different videos) at any one time and no more users can watch a video ?
For example, can say 300 users, view the 300 videos, each viewing a different video but all at the same time ? Or say can 600 users view the 300 videos, of which, 2 users each, view the same video simultaneously?

Thanks,
Paul